What to do to solve the riddle of vine rootstock induced drought tolerance

In order to avoid the loss of grapevine intra-varietal diversity of DOCa Rioja grape varieties, Regional Government of La Rioja established a germplasm bank with more than 1.600 accessions, whose origin lies in the prospecting and sampling of ancient vineyards located throughout the whole region. 30 clones of Tempranillo and 13 clones of Graciano were preselected and multiplied in a new vineyard for further observations. The aim of this work is to describe the first results from the physiological characterization by an optical sensor of these preselected clones, which constitute the base of a new clonal selection that aims to increase the range of available certified clones and to improve the adaptation of these varieties to future objectives and environmental conditions.

Grapevine cultivars are vegetatively propagated to preserve their varietal characteristics. However, spontaneous somatic variations that occur and are maintained during cycles of vegetative growth offer opportunities for the natural improvement of traditional grape cultivars. One advantageous trait for winegrowing is reduced bunch compactness, which decreases the susceptibility to pests and fungal diseases and favor an even berry ripening.

The global warming phenomenon involves the frequency of extreme meteorological events accompanied by a change in rainfall distribution. Irrigation frequency (IF) affects the spatial and temporal soil water distribution but its effects on the phenolic composition of the grape have been scarcely studied. The aim of this work was to evaluate the effects of four deficit irrigation frequencies of 30 % ETo: one irrigation per day (T01), two irrigations per week (T03), one irrigation per week (T07) and one irrigation every two weeks (T15) on berry phenolic composition at harvest.

The under-trellis zone of vineyards is a sensitive area through which vines cover a significant portion of their nutrient and water needs. Mechanical and chemical methods are applied to suppress competing and tall-growing weeds to ensure optimal vine growth conditions. In addition to higher operating costs and depending on the soil conditions, these practices might lead to a long-term reduction in soil fertility and biodiversity. The presented study aims to analyse the suitability and interspecies competition of a selected green cover mixture of five local herbaceous species as potential green cover mixture in the under-trellis area of Lower Austrian vineyards.

The disruptive effect exerted by high-power ultrasound (US) on plant cell walls, natural barriers to the diffusion of compounds of interest during the maceration of red wines, is established as the reason behind the chromatic improvement that its treatment causes. However, sometimes this improvement is not observed, especially with short maceration times. The presence of a high quantity of suspended cell wall material, which formation is favored by the sonication, could be the cause of this lack of positive results since this cell wall material has a high affinity for phenolic compounds.